In general, a plasma lighting system using microwave is a device for obtaining visible rays or ultraviolet rays by adding microwave to an electrodeless light bulb. The lighting system has a long life span when compared with a general incandescent lamp or a fluorescent lamp, and has an excellent lighting effect.
FIG. 1 is a longitudinal sectional view showing a conventional plasma lighting system.
The conventional plasma lighting system comprises: a case 1; a magnetron 3 arranged in the case 1 for generating microwave; a waveguide 5 arranged in the case 1 for transmitting the microwave generated from the magnetron 3; a light bulb 7 having lighting material therein and protruded in front of the case 1 for generating light; a mesh screen 9 fixed at an exit of the waveguide 5 for shielding microwave and passing light; and a reflective mirror 11 fixed to a frontal surface of the case at a circumference of the mesh screen 9 for reflecting the light generated at the bulb 7 forward.
A high voltage generator 13 for supplying high voltage to the magnetron 3 is installed inside of the case 1.
The waveguide 5 is provided with a shaft hole 5a at the center thereof, and a rotational shaft 10 for rotating the light bulb 7 passes the shaft hole 5a. Also, a bulb motor 8 to which the rotational shaft 10 is engaged is installed at the rear side of the waveguide 5 to rotate and cool the light bulb 7.
Especially, a blowing unit 14 for cooling the magnetron 3, the high voltage generator 13, and the bulb motor 8 are installed at the rear side of the case 1. The blowing unit 14 includes a fan housing 15 corresponding to a passage where external air is introduced in the case, a fan 16 provided in the fan housing 15, and a fan motor 17 for rotating the fan 16.
In said plasma lighting system, when a driving signal is inputted to the high voltage generator 13, the high voltage generator 13 boosts an AC power source from the exterior and supplies the boosted high voltage to the magnetron 3.
The magnetron 3 resonates by the high voltage supplied from the high voltage generator 13 and generates microwave of high frequency. The generated microwave is transmitted to the inner portion of the mesh screen 9 through the waveguide 9 to discharge the lighting material sealed in the light bulb 7, thereby generating light having a unique emit spectrum.
The light generated from the bulb 7 is reflected forward through the reflection mirror 11 and illuminates a lighting space.
In the meantime, when the plasma lighting system is operated, the fan motor 17 is together operated. At this time, by the fan 16 operated by the fan motor 17, external air of the case 1 passes a suction port 15a and two discharge ports 15b and 15b′ of the fan housing 15, cools the magnetron 3 and the high voltage generator 13, and is discharged out through an outlet port 1a formed in front of the case 1.
However, in the conventional plasma lighting system, since the two discharge ports 15b and 15b′ provided to the fan housing 15 are formed to have the same area, the magnetron 3 which generates heat relatively higher than any other parts can not be effectively cooled.
Accordingly, when high heat generating components such as the magnetron 3 are not sufficiently cooled, a durable life span is shortened or a performance is greatly degraded. To solve this, entire capacities of the fan and the fan motor have to be increased to sufficiently cool the high heat generating components.
Also, the conventional plasma lighting system has a structure that external air is sucked from the rear side of the case 1 and discharged to the frontal side of the case 1, so that warm air which has cooled various kinds of components is discharged to the lighting space to provide uncomfortable feeling to a user. To solve this, that is, to discharge the air from the frontal side of the case 1 to the other side, an additional discharge duct is required.